Head-up display devices are used which display an image on a display unit such as a display, reflect the image on a mirror, and display the image on a glass plate or the like as a virtual image. The head-up display device is used for displaying information and the like in a state of being superimposed on a normal view of a user. The head-up display device has various applications such as in an automobile which displays information such as a vehicle speed on a windshield.